Fisher, 60, had fatty buildup in the walls of her arteries and had taken multiple drugs before her death, the statement said. Officials were unable to conclusively determine the exact cause of her death, according to The Associated Press. The manner of death would be listed as “undetermined,” the coroner’s office said.

The coroner’s office did not immediately respond to HuffPost’s request for further details.

Sleep apnea is a disorder in which breathing pauses for up to several minutes during sleep, according to the National Institutes of Health. Untreated, it can increase the risk of high blood pressure, heart attack, stroke, obesity and diabetes. Fisher had a history of drug addiction and a heart condition.

Fisher was stricken by a cardiac medical emergency during a flight from London to Los Angeles in December. The actress was hospitalized after landing and died less than a week later, on Dec. 27. Her mother, the actress Debbie Reynolds, died from a stroke the following day.

Fisher rose to fame at age 20 after playing the original Princess Leia in the “Star Wars” film, “A New Hope.” She kept the role as the series continued in the early ‘80s. She most recently appeared in the franchise as Gen. Leia Organa in “The Force Awakens,” released in 2015.

She was vocal about her history with bipolar disorder and drug addiction, which she detailed in a memoir and one-woman stage show, both titled, Wishful Drinking.